British ports on Monday called on the UK government to begin an “urgent discussion” with France to reduce Brexit-related bureaucracy when exporting fish to the EU.

The demand came as Scottish fishing businesses staged a protest over the how Brexit has severely disrupted their exports by driving more than 20 lorries through central London bearing the slogan: “Incompetent Government: destroying shellfish industry!”

Since the UK left the EU single market and customs union on December 31, British fishing businesses have suffered delays at the border when exporting fresh produce to the bloc as it applies new import controls.

In a letter to Cabinet Office minister Michael Gove, the British Ports Association blamed a shortage of UK environmental health officers and the “extremely strict application” of the new EU import rules for the delays.

“[We urge you to hold] urgent discussions with your counterparts in the EU, particularly France, about a pragmatic approach to enforcement,” the BPA said in a letter seen by the Financial Times.

The call was echoed by the trade body Scotland Food & Drink, whose chief executive James Withers called for an “immediate dialogue” with the European Commission to secure a lighter-touch approach to border controls.

“The UK government has already paused checks on EU imports until July 2021 and we need the same for goods going in the opposite direction, into the EU,” he said.

Port operators expressed frustration at the red tape inflicted on UK fish export businesses as a result of Brexit.

Rob Parsons, harbour master at Newlyn in Cornwall, said businesses were struggling to get their catch to market.

The previously accepted practice of sending fish direct to the EU in open plastic crates was now being rejected by EU authorities that were requiring produce from so-called third countries to be placed in sealed polystyrene boxes at significant extra cost, he added.

“Eighty per cent of what goes through Newlyn is exported and the government has just not realised the knock-on effect on this community,” said Mr Parsons.

There are, however, some signs of improvement. DFDS, the leading shipper of Scottish seafood to the EU, on Monday restarted services for smaller exporters which it had suspended last week.

DFDS said it was now taking two days to reach the vital market of Boulogne-sur-Mer in France, but added the company would try to return to the pre-Brexit next-day service for smaller exporters “as soon as possible”.

Several French government officials expressed surprise at the lack of preparation on the British side for the new regulations that the EU is applying to imports from the UK since the end of the Brexit transition period on December 31.

In France, seafood processing companies whose activities are centred on Boulogne-sur-Mer near Calais said there had been severe disruption to supplies of products such as crabs and white fish from Scotland and England since January 1.

Peter Samson, who heads the Union du Mareyage Français, a federation of almost 500 seafood businesses, said some lorries had experienced “very serious delays” leading certain shipments to be destroyed because they were no longer fresh. He added the situation was slowly improving.

A UK government spokesperson said the fishing industry faced “some temporary issues” after the Brexit transition period and “we are looking at what additional financial support we can provide to those businesses affected”. This is expected to be worth £23m. “We continue to extensively engage and work closely with representatives of the industry from across the UK, and the authorities in EU member states, to understand and address any issues with documentation,” added the UK government spokesperson. “Our priority is to ensure that goods can continue to flow smoothly to market.”